Detection of the Heterogeneous O-Glycosylation Profile of MT1-MMP Expressed in Cancer Cells by a Simple MALDI-MS Method
Figure 6
Comparison of MS spectra of tryptic MT1-MMP digests containing different amounts of MT1-MMP.
(A) MT1-FLAG was serially diluted and then separated by SDS-PAGE and stained with Coomassie Blue. Sialidase, which contains BSA as a carrier protein, was loaded in the far-left lane (denoted by asterisk). Numbers on the left of the panels represent molecular masses in kilodaltons (kDa). (B) The polypeptide bands corresponding to MT1-FLAG were excised, in-gel digested with trypsin, and analyzed by MS using the liquid matrix 3AQ/CHCA. Glycopeptides contained in the whole protein digest obtained from MT1-FLAG (approximately 1.6 ng based on comparison with a BSA standard) were detected in the center of the liquid matrix. Numbers represent the cumulative intensity of the top peaks (arbitrary units). Arrowheads indicate glycopeptide ions (refer Fig. 3).